MPLS enabled version of Linux kernel. Based on original work of James Leu ( but almost completely rewritten!
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Documentation Merge tag 'mfd-fixes-3.9-1' of git://… Mar 16, 2013
arch perf,x86: fix wrmsr_on_cpu() warning on suspend/resume Mar 17, 2013
block Merge branch 'for-3.9/core' of git:// Feb 28, 2013
crypto Merge tag 'lzo-update-signature-20130226' of git://… Mar 1, 2013
drivers Merge tag 'char-misc-3.9-rc2' of git://… Mar 16, 2013
firmware firmware: remove last vestiges of dabusb Nov 21, 2012
fs Merge branch 'for-linus' of git://… Mar 17, 2013
include net: ipv6: Enable creation of IPv6 MPLS routes May 24, 2013
init final removal of CONFIG_EXPERIMENTAL Mar 12, 2013
ipc ipc: don't allocate a copy larger than max Mar 8, 2013
kernel kernel: Define MPLS sysctl interface Mar 20, 2013
lib lib: Introduced NLA_PROHIBIT flag Mar 20, 2013
mm mm/fremap.c: fix possible oops on error path Mar 15, 2013
net net: ipv6: Enable creation of IPv6 MPLS routes May 24, 2013
samples Merge branch 'perf-core-for-linus' of git://… Feb 20, 2013
scripts Merge branch 'kbuild' of git://… Mar 16, 2013
security Fix: compat_rw_copy_check_uvector() misuse in aio, readv, writev, and… Mar 12, 2013
sound ALSA: hda - Fix missing EAPD/GPIO setup for Cirrus codecs Mar 15, 2013
tools Merge tag 'usb-3.9-rc2' of git://… Mar 13, 2013
usr gen_init_cpio: remove redundant empty line Nov 19, 2012
virt/kvm hlist: drop the node parameter from iterators Feb 28, 2013
.gitignore .gitignore: remove stale entry for generated version.h Dec 18, 2012
.mailmap Viresh has moved Jun 20, 2012
COPYING [PATCH] update FSF address in COPYING Sep 10, 2005
CREDITS Randy has moved Mar 8, 2013
Kbuild kbuild: Fix missing system calls check on mips. Nov 9, 2011
Kconfig kbuild: migrate all arch to the kconfig mainmenu upgrade Sep 20, 2010
MAINTAINERS Merge tag 'hwmon-for-linus' of git://… Mar 16, 2013
Makefile Linux 3.9-rc3 Mar 17, 2013
README MPLS specific README file May 24, 2013
README.linux MPLS specific README file May 24, 2013



Multi Protocol Label Switching (MPLS) represents a simple technology, which is
today indispensable in network cores. MPLS protocol adds a 32-bit header
(Figure 1) between the second and the third network layer headers. 
Within these 32 bits, 20 bits are reserved for the label, 3 bits for
the Traffic Class (TC) field, 1 bit for the Bottom of Stack (S) field
and the remaining 8 bits are reserved for the Time to Live (TTL) field.

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Label
|                Label                  | Exp |S|       TTL     | Stack
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Entry

                    Label:  Label Value, 20 bits
                    Exp:    Experimental Use, 3 bits
                    S:      Bottom of Stack, 1 bit
                    TTL:    Time to Live, 8 bits

                              Figure 1

A traffic class carried by means of a MPLS packet is defined based on the TC field.
Definition of an S field enables assigning of several labels to the packets. In the
label grouping, only the lowest label, closest to the IP packet, has S bit set to 1.
All other labels in the label stack have S set to 0. TTL field is used just like a
TTL field of the IP packet.


MPLS can be built as a kernel module, or it can be built in a kernel.

To build MPLS first you need to run:

$ make menuconfig

and enable MPLS compiling from:

Network setup -> Networking options -> MPLS (Experimental)

If you're running Debian based system, nice HOW-TO on compiling and installing custom kernel
can be found here:


To be able to run MPLS, you will need modified iproute2 programme which can be downloaded from:

Creation of MPLS tunnel ingress points is done with:

# ip link add tunnel_name type mpls push 300

or with

# ip route add mpls push 300

To get more comprehensive explanation use:

$ ip link add tunnel_name type mpls help


$ ip route help

In order to be able to receive MPLS packets, interface must be MPLS enabled. This is done with:

# ip link set eth0 mpls on

To be able to receve MPLS packets recursively mpls0 interface must be brought up!

To build MPLS tunnel cross connect and egress points use:

# ip -M route add 200 mpls swap 300 dev eth0

MPLS SNMP stats are located in:


MPLS sysctl parameters are located in:


MPLS fully supports net namespaces.

IP-MPLS multipath routes are suported

Reserved labels, except the RouterAlert label, are handled properly.

1. Firewall support
2. ICMPv6 message sending, when TTL is exceeded or packet can't be forwarded because of MTU,
   from the inside of MPLS tunnel
3. MPLS multipath
3. Bridging support